<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
	<title></title>
</head>
<body>

</body>
</html>

<script type="text/javascript">
	var num;
	//num =40;
	//num=null;
	//num=true;
	alert(typeof num)
	// var new1=20;
	// alert(new1)
</script>